For some reason, whatever early computer my dad had those 15-something years ago didn't play sound effects in vanilla doom and when I played Doom 2, it was strictly the music I heard. Couple this with enemies appearing with no sound cue or turning a corner and suddenly running into a cacodemon, it was pretty jumpworthy. I remember literally jumping out of my chair and shouting when a sound effects-less lost soul flew at me out of nowhere in map 29.